B-Type Natriuretic Peptide (BNP) Test

There are various causes of heart failure and the condition can be of chronic (long term) or acute (sudden) onset. The condition is usually suspected based on physical symptoms such as difficulty breathing, breathlessness, fatigue or swelling (oedema) in the legs. If the diagnosis is unclear, BNP or NT-proBNP measurements can help doctors tell the difference between heart failure and other problems, such as lung disease. An accurate diagnosis is important because heart failure can be successfully treated, yet it is often under diagnosed and undertreated.

In the UK, healthcare professionals use BNP (or NT-proBNP) to exclude the presence of chronic heart failure. A normal BNP result in an untreated patient makes a diagnosis of heart failure unlikely. An elevated BNP concentration requires further investigation; your healthcare professional should arrange for you to see a specialist and to have an echocardiogram (ECG) , which will confirm whether heart failure is present. By performing a BNP test first not all patients, in whom heart failure is suspected, have to be referred for further testing in a hospital. The BNP result (e.g. how high it is), is also used to determine how quickly you should be seen by a specialist.Also, consider other tests to exclude other conditions such as:

• Chest x-ray
• Blood tests such as urea & electrolytes, eGFR
• Lung function tests

A 2014 guideline produced by the National Institute of Health and Care Excellence (NICE) also promotes the use of BNP (or NT-proBNP) in the initial assessment of a patient presenting with new suspected acute heart failure (heart failure of sudden onset / deterioration). A normal BNP result is used to rule out the diagnosis, whereas a raised BNP concentration should be followed up with an ECG to confirm the diagnosis.

The role of BNP in heart failure prognosis and monitoring is unclear. Therefore the test is not routinely used for these purposes in the UK.

A BNP test may be requested under the following circumstances:

• In your doctor's surgery, if you have symptoms that could be due to heart failure.
• In hospital, BNP may be used in patients presenting with suspected new acute heart failure.

A normal BNP result implies the patient does not have heart failure and the symptoms are due to a different condition. Elevated concentrations of BNP suggest that a person has heart failure, but further tests are required before the diagnosis is made. In general, the concentration of BNP increases as heart failure develops / deteriorates and decreases when the condition is stabilised.

Drugs such as ACE inhibitors, beta-blockers and diuretics can decrease BNP and NT-proBNP concentrations. BNP and NT-proBNP may also be reduced in body mass index (BMI) than 35 kg/m2 and those from an African-Caribbean family origin. It is important to inform your healthcare professional if you are taking these medications, so the test result can be interpreted correctly. Do not stop taking these medications without consulting with your healthcare professional.

BNP and NT-proBNP results provide the same information for your doctor but results for the different tests cannot be compared directly, and measurements should not be interchanged.

Increased levels of BNP and NT-proBNP are seen in patients with chronic kidney disease (CKD), age over 70 years of age, sepsis, diabetes mellitus, liver cirrhosis.

Heart failure slowly increases with age until about 65 years of age, and then more rapidly.

• 1 in 35 people 65–74 years of age.
• 1 in 15 people 75–84 years of age.
• Just over 1 in 7 people 85 years of age or older.